Welded structure and method

ABSTRACT

A welded structure and a method of treating a shaping member such as a casting die and a die component made of refractory metal or die steel to increase the life of the shaping member or alter the configuration of the shaping member. The weld contains about 50 to about 70 wt.% W, about 10 to about 40 wt.% Ni, about 1 to about 25 wt.% Fe, and 0 to about 5 wt.% per element of an additive selected from Co, Cu, Cr, Ti, Re, Ta, Mo, and V. The total weight of the additive is up to about 10 wt.%.

[ Sept. 9, 1975 WELDED STRUCTURE AND METHOD [75] Inventors: Peter C.Murphy; J. Richard Lawrence, both of Indianapolis, Ind.

[73] Assignee: P. R. Mallory & C0,, Inc.,

Indianapolis, Ind.

[22] Filed: Apr. 13, 1972 [21] Appl. No.: 243,883

Related U.S. Application Data [62] Division of Ser. No. 36,489, May 11,1970, Pat. No.

[56] References Cited UNITED STATES PATENTS 1,110,303 9/1914 Kreusler75/176 2,206,537 9/1940 Price 75/176 2,793,951 5/1957 Green ct al.75/176 X 2,843,921 7/1958 Ang 75/176 X 2,977,225 3/1961 Wlodek ct a1.75/176 3,110,101 11/1963 Kieffer et al..... 75/176 X 3,188,204 6/1965Bishop et al. 75/176 X 3,254,995 6/1966 Goodfellow et a1, 75/1763,307,982 3/1967 Milligan et a1 75/176 X 3,374,092 3/1968 Marshall75/176 X 3,378,671 4/1968 Harrison ct al. 75/176 X 3,656,731 4/1972Larsen 249/135 FOREIGN PATENTS OR APPLICATIONS 12,684 7/1909 Denmark75/176 OTHER PUBLICATIONS Tungsten, Physical Properties and PhaseDiagrams," Sylvania Elec. Prod. Inc., 1959, pp. 38 and 39. NuclearAbstracts, May 15, 1960, No. 8754. Nuclear Abstracts, Dec. 15, 1966, No.43885. Metal Finishing, 54, Oct. 1956, pp. 80.

Primary ExaminerC. Lovell Attorney, Agent, or FirmCharles W. Hoffmann;Robert F. Meyer; Donald W. Hanson [57] ABSTRACT A welded structure and amethod of treating a shaping member suchv as a casting die and a diecomponent made of refractory metal or die steel to increase the life ofthe shaping member or alter the configuration of the shaping member. Theweld contains about 50 to about 70 wt.% W, about 10 to about 40 wt.% Ni,about 1 to about 25 wt.% Fe, and 0 to about 5 wt.% per element of an'additive selected from Co, Cu, Cr, Ti, Re, Ta, Mo, and V. The totalweight of the additive is up to about 10 wt.%.

9 Claims, N0 Drawings WELDED STRUCTURE AND METHOD This is a division, ofapplication Ser. No. 36,489, filed May 11, 1970, now US. Pat. No.3,669,656.

This invention relates to a method of welding and repairing shapingmembers such as die casting dies and die components made of refractorymaterials or steel.

In recent years the development of refractory metal including tungstenand molybdenum base alloys for shaping members including dies and diecomponents such as core pins has been recognized in the die castingindustry. The much greater life of such shaping members as compared tosimilar products made of steel has been the controlling factor in thedevelopment in the die casting industry of interest in this product.Tungsten base compositions for shaping members are disclosed and claimedin application Ser. Nos. 855,701 now US. Pat. No. 3,656,731, and855,712, filed Sept. 5, 1969, assigned to the same assignee as thepresent application, which applications are hereby expresslyincorporated into the present application by reference and made a parthereof.

However, one problem which has been encountered in the use of refractorymaterials for shaping members is that when small defects occur in theshaping members such as eroded portions, machining errors, fatiguecracks and other defects, there has been no available technique to curethese defects, rendering the shaping members suitable for still longerlife.

Also, it is sometimes desirable to effect design changes in the shapingmembers by simple means such as welding used on refractory shapingmembers and on hot work die steels.

It is an object of the present invention to provide a method forobtaining greater life of die casting shaping members and for obtaininggreater flexibility in the use of such shaping members.

It is another object of the present invention to provide a method ofmaking a welding alloy suitable for welding shaping members.

It is another object of the present invention to provide a novel weldedstructure.

Other objects will be apparent from the following description.

in accordance with the present invention it has been found that atungsten base alloy comprising 50 to 70% tungsten, to 40% nickel andabout 1 to 25% iron can successfully be welded to refractory materialsand to die steels.

Preferably, the alloy contains about 50 to about 70% tungsten, about 20to about 30% nickel, and about 10 to about iron.

Furthermore, additional weld strength can be ob tained by adding one ormore of the following elements in an amount per element up to about 5%by weight of the composition; cobalt, copper, chromium, titanium,tantalum rhenium, vanadium and molybdenum. The total amount of suchadditives should not be greater than about 10% or the welded structuremay be too brittle.

Exemplary molybdenum base alloys include cast or sintered molybdenum,solid solution alloys of tungsten and molybdenum and molybdenum alloyscontaining minor alloying additives such as titanium, columbium,vanadium, and zirconium up to about 2% and carbon up to about 0.2%.

Shaping members are also often made of die steels. For example C .3.5,Cr, Mo, V, Co up to 5%, Mn up to 1%, Si up to 1.3%.

As is disclosed in the said Ser. No. 855,712, tungsten base alloys whichare particularly suitable for shaping members may comprise about 1 to12% nickel and 0.5 to about 8 weight percent iron. The shaping membersmay include die casting dies, molds, cores, core pins and related diestructures.

As is disclosed in the said Ser. No. 855,701, now US Pat. No. 3,656,731,an additional shaping member composition comprises a tungsten base alloycontaining about 1 to 12% nickel, about 0.5 to 8% iron and about 0.5 to8%molybdenum. The addition of molybdenum provides greater strength andresistance to thermal shock.

The said applications Ser. Nos. 855,701, now US. Patent No. 3,656,731and 855,712 disclose room temperature and elevated temperatureproperties of the tungsten base shaping members as well as the excellentresistance to thermal fatigue which these materials possess.

In general the welds utilizing the welding alloy of the presentinvention whether made to tungsten base materials, molybdenum basematerials or die steels, will have a room temperature ultimate tensilestrength of at least about 100,000 p.s.i., a 2% ofiset yield strength ofabout 90,000 p.s.i., a proportional limit of at least about 50,000p.s.i. and elongation in one inch of at least about 1%.

Preferably, a tensile strength of 115,000 p.s.i., a 2% yield strength of100,000 p.s.i. and a proportional limit of 60,000 p.s.i. are obtained.The preferred elongation is at least about 2% in one inch.

Insofar as elevated temperature properties are concerned, the welds willhave a short time ultimate tensile strength at 1200F of at least about75,000 p.s.i. and an elongation in 1 inch of about 2%. At 2,000F anultimate tensile strength of at least about 20,000 p.s.i. is generallyobtained, preferably at least about 24,000 p.s.i. and an elongation inone inch of at least about 3%, preferably about 4%.

it will be apparent to those skilled in the art, that these propertiesare more than adequate to withstand the stresses and thermal cyclingnormally encountered in the use of shaping members in die casting andrelated applications.

According to another embodiment of the present invention, it has beenfound that the welding alloy can be used to apply an overlay upon steeldie casting components, for example having the previously describedsteel compositions. The coating is applied by are welding and preferablyis from about two-thousandths of an inch to one-eighth of an inch thick.It is unexpected that such an overlay would function satisfactorilybecause of the large difference in coefficient of thermal expansion ofdie steel as compared to the alloy of the present invention. However, itis believed that the sound metallurgical bond formed between the alloyoverlay and the steel may at least in part account for the satisfactorycastings and die life obtained.

The welding alloy can be made in the following manner. Elemental powdersof metallic tungsten, nickel and iron of a size less than about 10microns, preferably from 1 to 8 microns are mixed together with asuitable organic binder or mixture of binders, for example parafin in anexemplary amount of 3 to 15% by weight. Al-

ternatively co-reduced powders of these metals may be used, in a sizebelow.l microns.

Upon affecting the mixing there next follows a pressing operation. Thiscan be done hydraulically or hydrostatically, or extrusion may beutilized. In general a.

pressure range of from about 1 to 50tons persquare inch may be used.

Of course, if hydrostatic pressing is utilized it is not necessary touse any binder in the initialpowder mix. Dies are used in the pressingoperation corresponding to the shape of weld rod desired, butconsiderably enform, it may be placed powdered refractory material or Vgroove slabs made for example of metal or ceramic material such asalumina. In general up to about 5% shrinkage is expected duringpre-sintering.

The sintering temperature is very important and should be carried: outat a temperature below 1485C to avoid melting the alloy The timeshouldbe from minutes to 24 hours and the temperatureis preferablybetween 1430 and 14 70C. This will result in a product having about 85%of theoretical density minimum.

In order to obtain a higher density, the sinte'red alloy may be swagedwith a reduction in area of l to 30%. Usually only one pass is necessaryand this results in a product having above 90%, preferably 95%, oftheoret ical density.

Weld alloy'material, preferably in rod form, is readily utiliied inconventional welding equipment, For example, a Linde HDA-300 welder 'maybe used. As is conventional in welding, an arc is struck between thewelding electrode, for example a tungsten electrode and the work piece,and the weld rod is fed into the arc, prefer-' ably at an acute anglewith respect to't'h'e electrode. The are melts the weld rod and adeposit is formed on the work piece as is wellknown to those skilled inthe welding art. Q

Exemplary current to be used during welding may be between 375 amps tostart and approximately 200 amps continuing. Preferably, the arc isstruck between the electrode and the work piece prior to introducing theweld rod into the arc. The voltage across the arc maybe for example 2080volts. Obviously, the particular welding currents and voltages may varyas desired. Likewise, the atmosphere may be varied by those skilled inthe welding art. The process may be carried out in an inert gas such asargon, helium or nitrogen or in a vacuum chamber. However, if desiredsuch a chamber maybe dispensed with and the welding operation carriedout'in air. I

The welds resulting from the above described procedures are sound,non-porous, consistant, and strong, and have the previously describedmechanical properties. The technique requires only a normal degree ofwelding skill. Exhaustive metallurgical analysis has proven this fact.In addition, subsequent thermal fatigue tests show the welded structuresto have life characteristics similar to the component or shaping basematerial in the die itself.

Resistance to thermal fatigue in die casting applications has proven tobe excellent in that examination after 40,000 cycles in brass diecasting has resulted in no defects due to thermal fatigue.

'We' claim:,

l. A method of treating a shaping member of either die steel, a W basedalloy, or a Mo based alloy, the method comprising the steps of providinga shaping member with a portion to be welded, and welding the portion ofthe shaping member with an alloy consisting essentially of about 50 toabout 70 wt.% W, about 10 to about 40 wt.% Ni, about 1 to about 25 wt.%Fe, and 0 to about 5 wt.% per element of an additive selected from Co,Cu, Cr, Ti, Ta, Re, V and M0, the total additive content being no morethan up to about 10 wt.%.

2. The method of. claim 1, wherein the alloy consists essentially ofabout 50 to about 70 wt.% W, about 20 toabout 30 wt.% Ni, about 10 toabout 15 wt.% Fe, and 0 to about 5 wt.% per element of an additiveselected from Co, Cu, Cr, Ti, Ta, Re, V and Mo.

3. The method of claim 1, wherein the shaping mem her is a W based ailoyconsisting essentially of about 1 to about 12 wt.% Ni, about 05m about 8wt.% Fe, 0 to about 8 wt.% M0, the remainder essentially W.

4. A welded structure comprising a shaping member of either die steel, aW based alloy, or a Mo based alloy, a weld, over the shaping member, theweld consisting essentially of about 50 to about 70 wt.% W, about 10 toabout 40 wt.% Ni, about 1 to about 25 Wt.% Fe, and 0 to about 5 wt.% perelement of an additive selected from Co,Cu, Cr, Ti, Ta, Re, V and M0,the total additive content being no more than up to about 10 wt.%.

5. The welded structure of claim 4, wherein the weld consistsessentially of about 50 to about 70 wt.% W, about 20 to about 30 wt.%Ni, about 10 to about 15 wt.% Fe, and 0 to about 5 wt.% per element ofan additive selected from Co, Cu, Cr, Ti, Ta, Re, V and Mo.

6. The welded structure of claim 4, wherein the shaping member is a Wbased alloy consisting essentially of about 1 to about 12 wt.% Ni, about0.5 to about 8 wt.% Fe, 0 to about 8 wt.% M0, the remainder essentiallyW.

7 The welded structure ofclaim 4, wherein the shaping member is diesteel, and the weld is an overlay on the die steel.

8. The welded structure of claim 4, wherein the weld repairs a defect inthe shaping member.

9. The welded structure of claim 4, wherein the weld alters theconfiguration of the shaping member.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.3,904,383 DATED 09/09/75 INVENTOR(S) Peter C. Murphy & Richard J.Lawrence It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Co]. 1, h'ne 58 insert after tantaIum C01 3. h'ne 22, insert around VSigned and Scaled this [SEAL] t meth' Day of DecmberI975 A ttest:

RUTH C. MASON C. IAIBIIALI. DANN Arresting Officer Cnmmisxiunrr of hull:and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 3,904,383 DATED 09/09/75 INVENTOR(S) Peter C. Murphy &Richard J. Lawrence It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

C01. 1, Iine 58 insert after tantaIum C01 3. line 22, insert around VSigned and Sealed this Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ommmhmer of hmm andTrademarks

1. A method of treating a shaping member of either die steel, a W basedalloy, or a Mo based alloy, the method comprising the steps of providinga shaping member with a portion to be welded, and welding the portion ofthe shaping member with an alloy consisting essentially of about 50 toabout 70 wt.% W, about 10 to about 40 wt.% Ni, about 1 to about 25 wt.%Fe, and 0 to about 5 wt.% per element of an additive selected from Co,Cu, Cr, Ti, Ta, Re, V and Mo, the total additive content being no morethan up to about 10 wt.%.
 2. The method of claim 1, wherein the alloyconsists essentially of about 50 to about 70 wt.% W, about 20 to about30 wt.% Ni, about 10 to about 15 wt.% Fe, and 0 to about 5 wt.% perelement of an additive selected from Co, Cu, Cr, Ti, Ta, Re, V and Mo.3. The method of claim 1, wherein the shaping member is a W based alloyconsisting essentially of about 1 to about 12 wt.% Ni, about 0.5 toabout 8 wt.% Fe, 0 to about 8 wt.% Mo, the remainder essentially W.
 4. AWELDED STRUCTURE COMPRISING A SHAPING MEMBER OF EITHER DIE STEEL, A WBASED ALLOY, OR A MO BASED ALLOY, A WELD OVER THE SHAPING MEMBER THEWELD CONSISTING ESSENTIALLY OF ABOUT 50 TO 70 ST.% W, ABOUT 10 TO ABOUT40 WT.% NI, ABOUT 1 TO ABOUT 25 WT.% FE, AND 0 TO ABOUT 5 WT.% PERELEMENT OF AN ADDITIVE SELECTED FROM CO, CU, CR, TI, TA, RE, V AND MO,THE TOTAL ADDITIVE CONTENT BEING NO MORE THAN UP TO ABOUT 10 WT%.
 5. Thewelded structure of claim 4, wherein the weld consists essentially ofabout 50 to about 70 wt.% W, about 20 to about 30 wt.% Ni, about 10 toabout 15 wt.% Fe, and 0 to about 5 wt.% per element of an additiveselected from Co, Cu, Cr, Ti, Ta, Re, V and Mo.
 6. The welded structureof claim 4, wherein the shaping member is a W based alloy consistingessentially of about 1 to about 12 wt.% Ni, about 0.5 to about 8 wt.%Fe, 0 to about 8 wt.% Mo, the remainder essentially W.
 7. The weldedstructure of claim 4, wherein the shaping member is die steel, and theweld is an overlay on the die steel.
 8. The welded structure of claim 4,wherein the weld repairs a defect in the shaping member.
 9. The weldedstructure of claim 4, wherein the weld alters the configuration of theshaping member.